1
|
Wang B, Zhang J, Zhang D, Lu C, Liu H, Gao Q, Niu T, Yin M, Cui S. Casein Kinase 1α as a Novel Factor Affects Thyrotropin Synthesis via PKC/ERK/CREB Signaling. Int J Mol Sci 2023; 24:7034. [PMID: 37108197 PMCID: PMC10138882 DOI: 10.3390/ijms24087034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 03/29/2023] [Accepted: 04/07/2023] [Indexed: 04/29/2023] Open
Abstract
Casein kinase 1α (CK1α) is present in multiple cellular organelles and plays various roles in regulating neuroendocrine metabolism. Herein, we investigated the underlying function and mechanisms of CK1α-regulated thyrotropin (thyroid-stimulating hormone (TSH)) synthesis in a murine model. Immunohistochemistry and immunofluorescence staining were performed to detect CK1α expression in murine pituitary tissue and its localization to specific cell types. Tshb mRNA expression in anterior pituitary was detected using real-time and radioimmunoassay techniques after CK1α activity was promoted and inhibited in vivo and in vitro. Relationships among TRH/L-T4, CK1α, and TSH were analyzed with TRH and L-T4 treatment, as well as thyroidectomy, in vivo. In mice, CK1α was expressed at higher levels in the pituitary gland tissue than in the thyroid, adrenal gland, or liver. However, inhibiting endogenous CK1α activity in the anterior pituitary and primary pituitary cells significantly increased TSH expression and attenuated the inhibitory effect of L-T4 on TSH. In contrast, CK1α activation weakened TSH stimulation by thyrotropin-releasing hormone (TRH) by suppressing protein kinase C (PKC)/extracellular signal-regulated kinase (ERK)/cAMP response element binding (CREB) signaling. CK1α, as a negative regulator, mediates TRH and L-T4 upstream signaling by targeting PKC, thus affecting TSH expression and downregulating ERK1/2 phosphorylation and CREB transcriptional activity.
Collapse
Affiliation(s)
- Bingjie Wang
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; (B.W.)
| | - Jinglin Zhang
- Institute of Reproduction and Metabolism, Yangzhou University, Yangzhou 225009, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, The Ministry of Education of China, Yangzhou University, Yangzhou 225009, China
| | - Di Zhang
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; (B.W.)
- Institute of Reproduction and Metabolism, Yangzhou University, Yangzhou 225009, China
| | - Chenyang Lu
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; (B.W.)
| | - Hui Liu
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; (B.W.)
| | - Qiao Gao
- Institute of Reproduction and Metabolism, Yangzhou University, Yangzhou 225009, China
| | - Tongjuan Niu
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; (B.W.)
| | - Mengqing Yin
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; (B.W.)
| | - Sheng Cui
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; (B.W.)
- Institute of Reproduction and Metabolism, Yangzhou University, Yangzhou 225009, China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China
| |
Collapse
|
2
|
Hirahara N, Nakamura HM, Sasaki S, Matsushita A, Ohba K, Kuroda G, Sakai Y, Shinkai S, Haeno H, Nishio T, Yoshida S, Oki Y, Suda T. Liganded T3 receptor β2 inhibits the positive feedback autoregulation of the gene for GATA2, a transcription factor critical for thyrotropin production. PLoS One 2020; 15:e0227646. [PMID: 31940421 PMCID: PMC6961892 DOI: 10.1371/journal.pone.0227646] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 12/23/2019] [Indexed: 12/26/2022] Open
Abstract
The serum concentration of thyrotropin (thyroid stimulating hormone, TSH) is drastically reduced by small increase in the levels of thyroid hormones (T3 and its prohormone, T4); however, the mechanism underlying this relationship is unknown. TSH consists of the chorionic gonadotropin α (CGA) and the β chain (TSHβ). The expression of both peptides is induced by the transcription factor GATA2, a determinant of the thyrotroph and gonadotroph differentiation in the pituitary. We previously reported that the liganded T3 receptor (TR) inhibits transactivation activity of GATA2 via a tethering mechanism and proposed that this mechanism, but not binding of TR with a negative T3-responsive element, is the basis for the T3-dependent inhibition of the TSHβ and CGA genes. Multiple GATA-responsive elements (GATA-REs) also exist within the GATA2 gene itself and mediate the positive feedback autoregulation of this gene. To elucidate the effect of T3 on this non-linear regulation, we fused the GATA-REs at -3.9 kb or +9.5 kb of the GATA2 gene with the chloramphenicol acetyltransferase reporter gene harbored in its 1S-promoter. These constructs were co-transfected with the expression plasmids for GATA2 and the pituitary specific TR, TRβ2, into kidney-derived CV1 cells. We found that liganded TRβ2 represses the GATA2-induced transactivation of these reporter genes. Multi-dimensional input function theory revealed that liganded TRβ2 functions as a classical transcriptional repressor. Then, we investigated the effect of T3 on the endogenous expression of GATA2 protein and mRNA in the gonadotroph-derived LβT2 cells. In this cell line, T3 reduced GATA2 protein independently of the ubiquitin proteasome system. GATA2 mRNA was drastically suppressed by T3, the concentration of which corresponds to moderate hypothyroidism and euthyroidism. These results suggest that liganded TRβ2 inhibits the positive feedback autoregulation of the GATA2 gene; moreover this mechanism plays an important role in the potent reduction of TSH production by T3.
Collapse
Affiliation(s)
- Naoko Hirahara
- Division of Endocrinology and Metabolism, Department of Internal medicine, Japanese Red Cross Shizuoka Hospital, Shizuoka, Shizuoka, Japan
| | - Hiroko Misawa Nakamura
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Shigekazu Sasaki
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
- * E-mail:
| | - Akio Matsushita
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Kenji Ohba
- Medical Education Center, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Go Kuroda
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Yuki Sakai
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Shinsuke Shinkai
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Hiroshi Haeno
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo Kashiwa, Kashiwa, Chiba, Japan
| | - Takuhiro Nishio
- Department of Integrated Human Sciences, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Shuichi Yoshida
- Department of Integrated Human Sciences, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Yutaka Oki
- Department of Family and Community Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Takafumi Suda
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| |
Collapse
|
3
|
Klein JR. Novel Splicing of Immune System Thyroid Stimulating Hormone β-Subunit-Genetic Regulation and Biological Importance. Front Endocrinol (Lausanne) 2019; 10:44. [PMID: 30804891 PMCID: PMC6371030 DOI: 10.3389/fendo.2019.00044] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 01/18/2019] [Indexed: 12/29/2022] Open
Abstract
Thyroid stimulating hormone (TSH), a glycoprotein hormone produced by the anterior pituitary, controls the production of thyroxine (T4) and triiodothyronine (T3) in the thyroid. TSH is also known to be produced by the cells of the immune system; however, the physiological importance of that to the organism is unclear. We identified an alternatively-spliced form of TSHβ that is present in both humans and mice. The TSHβ splice variant (TSHβv), although produced at low levels by the pituitary, is the primary form made by hematopoietic cells in the bone marrow, and by peripheral leukocytes. Recent studies have linked TSHβv functionally to a number of health-related conditions, including enhanced host responses to infection and protection against osteoporosis. However, TSHβv also has been associated with autoimmune thyroiditis in humans. Yet to be identified is the process by which the TSHβv isoform is produced. Here, a set of genetic steps is laid out through which human TSHβv is generated using splicing events that result in a novel transcript in which exon 2 is deleted, exon 3 is retained, and the 3' end of intron 2 codes for a signal peptide of the TSHβv polypeptide.
Collapse
|
4
|
Bargi-Souza P, Goulart-Silva F, Nunes MT. Posttranscriptional actions of triiodothyronine on Tshb expression in TαT1 cells: New insights into molecular mechanisms of negative feedback. Mol Cell Endocrinol 2018; 478:45-52. [PMID: 30031103 DOI: 10.1016/j.mce.2018.07.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 06/10/2018] [Accepted: 07/13/2018] [Indexed: 11/28/2022]
Abstract
Rapid actions of triiodothyronine (T3) on thyrotropin (TSH) synthesis and secretion have been described in hypothyroid male rats. However, the molecular mechanisms remain unknown. TαT1 cells, a thyrotroph cell line, was used herein to characterize the possible non-genomic actions of T3 on the expression of alpha (Cga) and Tshb genes, and the posttranscriptional processing and translation of both transcripts. The involvement of αVβ3 integrin was also assessed. T3 quickly reduced Tshb mRNA content, poly(A) tail length and its association with ribosomes. The effect of T3 on Tshb gene expression was detected even in the presence of a transcription inhibitor. The decrease in Tshb mRNA content and polyadenylation depend on T3 interaction with αVβ3 integrin, while T3 reduced Cga mRNA content by transcriptional action. The translational rate of both transcripts was reduced by a mechanism, which does not depend on T3-αVβ3 integrin interaction. Results indicate that, in parallel with the inhibitory transcriptional action in Cga and Tshb gene expression, T3 rapidly triggers additional posttranscriptional mechanisms, reducing the TSH synthesis. These non-genomic actions partially depend on T3-αVβ3 integrin interaction at the plasma membrane of thyrotrophs and add new insights to the molecular mechanisms involved in T3 negative feedback loop.
Collapse
Affiliation(s)
- Paula Bargi-Souza
- Department of Physiology and Biophysics of the Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, CEP 05508-000, Brazil
| | - Francemilson Goulart-Silva
- Department of Physiology and Biophysics of the Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, CEP 05508-000, Brazil
| | - Maria Tereza Nunes
- Department of Physiology and Biophysics of the Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, CEP 05508-000, Brazil.
| |
Collapse
|
5
|
Park E, Jung J, Araki O, Tsunekawa K, Park SY, Kim J, Murakami M, Jeong SY, Lee S. Concurrent TSHR mutations and DIO2 T92A polymorphism result in abnormal thyroid hormone metabolism. Sci Rep 2018; 8:10090. [PMID: 29973617 PMCID: PMC6031622 DOI: 10.1038/s41598-018-28480-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 06/21/2018] [Indexed: 12/11/2022] Open
Abstract
Deiodinase 2 (DIO2) plays an important role in thyroid hormone metabolism and its regulation. However, molecular mechanism that regulates DIO2 activity remains unclear; only mutaions in selenocysteine insertion sequence binding protein 2 and selenocysteine tranfer RNA (tRNA[Ser]Sec) are reported to result in decreased DIO2 activity. Two patients with clinical evidence of abnormal thyroid hormone metabolism were identified and found to have TSHR mutations as well as DIO2 T92A single nucleotide polymorphism (SNP). Primary-cultured fibroblasts from one patient present a high level of basal DIO2 enzymatic activity, possibly due to compensation by augmented DIO2 expression. However, this high enzymatic active state yet fails to respond to accelerating TSH. Consequently, TSHR mutations along with DIO2 T92A SNP ("double hit") may lead to a significant reduction in DIO2 activity stimulated by TSH, and thereby may have clinical relevance in a select population of hypothyroidism patients who might benefit from a T3/T4 combination therapy.
Collapse
Affiliation(s)
- Eunkuk Park
- Department of Medical Genetics, Ajou University School of Medicine, Suwon, Republic of Korea
- Department of Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon, Republic of Korea
| | - Jaehoon Jung
- Department of Internal medicine, Gyeongsang Institute of Health Science, Gyeongsang National University School of Medicine and Gyeongsang National University Changwon Hospital, Changwon, Republic of Korea
| | - Osamu Araki
- Department of Clinical Laboratory Medicine, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Katsuhiko Tsunekawa
- Department of Clinical Laboratory Medicine, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - So Young Park
- Department of Internal Medicine, Cheil General Hospital and Women's Healthcare Center, Dankook University College of Medicine, Seoul, Republic of Korea
| | - Jeonghyun Kim
- Department of Medical Genetics, Ajou University School of Medicine, Suwon, Republic of Korea
- Department of Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon, Republic of Korea
| | - Masami Murakami
- Department of Clinical Laboratory Medicine, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Seon-Yong Jeong
- Department of Medical Genetics, Ajou University School of Medicine, Suwon, Republic of Korea.
- Department of Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon, Republic of Korea.
| | - Sihoon Lee
- Department of Internal Medicine and Laboratory of Genomics and Translational Medicine, Gachon University School of Medicine, Incheon, Republic of Korea.
| |
Collapse
|
6
|
Xie H, Hoffmann HM, Iyer AK, Brayman MJ, Ngo C, Sunshine MJ, Mellon PL. Chromatin status and transcription factor binding to gonadotropin promoters in gonadotrope cell lines. Reprod Biol Endocrinol 2017; 15:86. [PMID: 29065928 PMCID: PMC5655979 DOI: 10.1186/s12958-017-0304-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 10/04/2017] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Proper expression of key reproductive hormones from gonadotrope cells of the pituitary is required for pubertal onset and reproduction. To further our understanding of the molecular events taking place during embryonic development, leading to expression of the glycoproteins luteinizing hormone (LH) and follicle-stimulating hormone (FSH), we characterized chromatin structure changes, imparted mainly by histone modifications, in model gonadotrope cell lines. METHODS We evaluated chromatin status and gene expression profiles by chromatin immunoprecipitation assays, DNase sensitivity assay, and RNA sequencing in three developmentally staged gonadotrope cell lines, αT1-1 (progenitor, expressing Cga), αT3-1 (immature, expressing Cga and Gnrhr), and LβT2 (mature, expressing Cga, Gnrhr, Lhb, and Fshb), to assess changes in chromatin status and transcription factor access of gonadotrope-specific genes. RESULTS We found the common mRNA α-subunit of LH and FSH, called Cga, to have an open chromatin conformation in all three cell lines. In contrast, chromatin status of Gnrhr is open only in αT3-1 and LβT2 cells. Lhb begins to open in LβT2 cells and was further opened by activin treatment. Histone H3 modifications associated with active chromatin were high on Gnrhr in αT3-1 and LβT2, and Lhb in LβT2 cells, while H3 modifications associated with repressed chromatin were low on Gnrhr, Lhb, and Fshb in LβT2 cells. Finally, chromatin status correlates with the progressive access of LHX3 to Cga and Gnrhr, followed by PITX1 binding to the Lhb promoter. CONCLUSION Our data show the gonadotrope-specific genes Cga, Gnrhr, Lhb, and Fshb are not only controlled by developmental transcription factors, but also by epigenetic mechanisms that include the modulation of chromatin structure, and histone modifications.
Collapse
Affiliation(s)
- Huimin Xie
- 0000 0001 2107 4242grid.266100.3Department of Reproductive Medicine, Center for Reproductive Science and Medicine, University of California, 9500 Gilman Drive La Jolla, San Diego, CA 92093-0674 USA
| | - Hanne M. Hoffmann
- 0000 0001 2107 4242grid.266100.3Department of Reproductive Medicine, Center for Reproductive Science and Medicine, University of California, 9500 Gilman Drive La Jolla, San Diego, CA 92093-0674 USA
| | - Anita K. Iyer
- 0000 0001 2107 4242grid.266100.3Department of Reproductive Medicine, Center for Reproductive Science and Medicine, University of California, 9500 Gilman Drive La Jolla, San Diego, CA 92093-0674 USA
- 0000 0004 0507 3954grid.185669.5Illumina Inc, 5200 Illumina Way, San Diego, CA 92122 USA
| | - Melissa J. Brayman
- 0000 0001 2107 4242grid.266100.3Department of Reproductive Medicine, Center for Reproductive Science and Medicine, University of California, 9500 Gilman Drive La Jolla, San Diego, CA 92093-0674 USA
- Foley and Lardner LLP, 402 West Broadway, Suite 2100, San Diego, CA 92101 USA
| | - Cindy Ngo
- 0000 0001 2107 4242grid.266100.3Department of Reproductive Medicine, Center for Reproductive Science and Medicine, University of California, 9500 Gilman Drive La Jolla, San Diego, CA 92093-0674 USA
| | - Mary Jean Sunshine
- 0000 0001 2107 4242grid.266100.3Department of Reproductive Medicine, Center for Reproductive Science and Medicine, University of California, 9500 Gilman Drive La Jolla, San Diego, CA 92093-0674 USA
| | - Pamela L. Mellon
- 0000 0001 2107 4242grid.266100.3Department of Reproductive Medicine, Center for Reproductive Science and Medicine, University of California, 9500 Gilman Drive La Jolla, San Diego, CA 92093-0674 USA
| |
Collapse
|
7
|
Sasaki S, Matsushita A, Kuroda G, Nakamura HM, Oki Y, Suda T. The Mechanism of Negative Transcriptional Regulation by Thyroid Hormone: Lessons From the Thyrotropin β Subunit Gene. VITAMINS AND HORMONES 2017; 106:97-127. [PMID: 29407449 DOI: 10.1016/bs.vh.2017.06.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Thyroid hormone (T3) activates (positive regulation) or represses (negative regulation) target genes at the transcriptional level. The molecular mechanism of the former has been elucidated in detail; however, the mechanism for negative regulation has not been established. The best example of the gene that is negatively regulated by T3 is the thyrotropin (thyroid-stimulating hormone) β subunit (TSHβ) gene. Analogous to the T3-responsive element (TRE) in positive regulation, a negative TRE (nTRE) has been postulated in the TSHβ gene. However, TSHβ promoter analysis, performed in the presence of transcription factors Pit1 and GATA2, which are determinants of thyrotroph differentiation in the pituitary, revealed that the nTRE is dispensable for inhibition by T3. We propose a tethering model in which the T3 receptor is tethered to GATA2 via protein-protein interaction and inhibits GATA2-dependent transactivation of the TSHβ gene in a T3-dependent manner.
Collapse
Affiliation(s)
| | | | - Go Kuroda
- Hamamatsu University School of Medicine, Shizuoka, Japan
| | | | - Yutaka Oki
- Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Takafumi Suda
- Hamamatsu University School of Medicine, Shizuoka, Japan
| |
Collapse
|
8
|
Matsunaga H, Sasaki S, Suzuki S, Matsushita A, Nakamura H, Nakamura HM, Hirahara N, Kuroda G, Iwaki H, Ohba K, Morita H, Oki Y, Suda T. Essential Role of GATA2 in the Negative Regulation of Type 2 Deiodinase Gene by Liganded Thyroid Hormone Receptor β2 in Thyrotroph. PLoS One 2015; 10:e0142400. [PMID: 26571013 PMCID: PMC4646574 DOI: 10.1371/journal.pone.0142400] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 10/21/2015] [Indexed: 12/30/2022] Open
Abstract
The inhibition of thyrotropin (thyroid stimulating hormone; TSH) by thyroid hormone (T3) and its receptor (TR) is the central mechanism of the hypothalamus-pituitary-thyroid axis. Two transcription factors, GATA2 and Pit-1, determine thyrotroph differentiation and maintain the expression of the β subunit of TSH (TSHβ). We previously reported that T3-dependent repression of the TSHβ gene is mediated by GATA2 but not by the reported negative T3-responsive element (nTRE). In thyrotrophs, T3 also represses mRNA of the type-2 deiodinase (D2) gene, where no nTRE has been identified. Here, the human D2 promoter fused to the CAT or modified Renilla luciferase gene was co-transfected with Pit-1 and/or GATA2 expression plasmids into cell lines including CV1 and thyrotroph-derived TαT1. GATA2 but not Pit-1 activated the D2 promoter. Two GATA responsive elements (GATA-REs) were identified close to cAMP responsive element. The protein kinase A activator, forskolin, synergistically enhanced GATA2-dependent activity. Gel-shift and chromatin immunoprecipitation assays with TαT1 cells indicated that GATA2 binds to these GATA-REs. T3 repressed the GATA2-induced activity of the D2 promoter in the presence of the pituitary-specific TR, TRβ2. The inhibition by T3-bound TRβ2 was dominant over the synergism between GATA2 and forskolin. The D2 promoter is also stimulated by GATA4, the major GATA in cardiomyocytes, and this activity was repressed by T3 in the presence of TRα1. These data indicate that the GATA-induced activity of the D2 promoter is suppressed by T3-bound TRs via a tethering mechanism, as in the case of the TSHβ gene.
Collapse
Affiliation(s)
- Hideyuki Matsunaga
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431–3192, Japan
| | - Shigekazu Sasaki
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431–3192, Japan
| | - Shingo Suzuki
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431–3192, Japan
| | - Akio Matsushita
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431–3192, Japan
| | - Hirotoshi Nakamura
- Kuma Hospital, 8-2-35 Shimoyamate-dori, Chuo-ku, Kobe, Hyogo, 650–0011, Japan
| | - Hiroko Misawa Nakamura
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431–3192, Japan
| | - Naoko Hirahara
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431–3192, Japan
| | - Go Kuroda
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431–3192, Japan
| | - Hiroyuki Iwaki
- Division of Endocrinology, Seirei Hamamatsu General Hospital, 2-12-12 Sumiyoshi, Naka-ku, Hamamatsu, Shizuoka, 430–0906, Japan
| | - Kenji Ohba
- Duke-NUS Graduate Medical School Singapore, No 8 College Road, Level 8th, 169857, Singapore
| | - Hiroshi Morita
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431–3192, Japan
| | - Yutaka Oki
- Department of Family and Community Medicine, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431–3192, Japan
| | - Takafumi Suda
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, Shizuoka, 431–3192, Japan
| |
Collapse
|
9
|
Park KS, Kim KK, Kim KE. Msx1 homeodomain transcription factor and TATA-binding protein interact to repress the expression of the glycoprotein hormone α subunit gene. Biochem Biophys Res Commun 2015; 468:326-30. [PMID: 26505791 DOI: 10.1016/j.bbrc.2015.10.102] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 10/20/2015] [Indexed: 10/22/2022]
Abstract
Studying the regulatory mechanism of the glycoprotein hormone α subunit (αGSU) gene in thyrotropes is essential for understanding the synthesis of functional thyroid-stimulating hormone (TSH). Here, we investigated the influence of a homeodomain transcription factor Msx1 (Msh homeobox 1) on αGSU expression in thyrotropes. The transient expression of Msx1 inhibited the activity of an αGSU reporter gene, as well as its endogenous mRNA level in thyrotrope-derived αTSH cells. Luciferase reporter assays with serial deletion constructs and a close examination of the sequences revealed that the putative Msx1 binding site (PMS) in the αGSU promoter is not responsible for Msx1-mediated transcriptional repression. We also identified the TATA-box binding protein (TBP) as an interacting protein in thyrotropes. Interaction of TBP with Msx1 attenuates the inhibitory effect of Msx1 on αGSU gene expression in a DNA binding-independent manner. Furthermore, transient transfection studies with mutant Msx1 revealed that the interaction of TBP and Msx1 is critical for Msx1-mediated transcriptional repression of the αGSU. These results suggest that Msx1 functions as a transcriptional repressor of αGSU and that its interaction with TBP is an integral part of the mechanism by which Msx1 regulates the inhibition of αGSU gene expression.
Collapse
Affiliation(s)
- Ki-Sun Park
- Department of Biochemistry, Chungnam National University, Daejeon, 305-764, Republic of Korea
| | - Kee K Kim
- Department of Biochemistry, Chungnam National University, Daejeon, 305-764, Republic of Korea.
| | - Kyoon Eon Kim
- Department of Biochemistry, Chungnam National University, Daejeon, 305-764, Republic of Korea.
| |
Collapse
|
10
|
Tomić M, Bargi-Souza P, Leiva-Salcedo E, Nunes MT, Stojilkovic SS. Calcium signaling properties of a thyrotroph cell line, mouse TαT1 cells. Cell Calcium 2015; 58:598-605. [PMID: 26453278 DOI: 10.1016/j.ceca.2015.09.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 09/14/2015] [Accepted: 09/20/2015] [Indexed: 01/14/2023]
Abstract
TαT1 cells are mouse thyrotroph cell line frequently used for studies on thyroid-stimulating hormone beta subunit gene expression and other cellular functions. Here we have characterized calcium-signaling pathways in TαT1 cells, an issue not previously addressed in these cells and incompletely described in native thyrotrophs. TαT1 cells are excitable and fire action potentials spontaneously and in response to application of thyrotropin-releasing hormone (TRH), the native hypothalamic agonist for thyrotrophs. Spontaneous electrical activity is coupled to small amplitude fluctuations in intracellular calcium, whereas TRH stimulates both calcium mobilization from intracellular pools and calcium influx. Non-receptor-mediated depletion of intracellular pool also leads to a prominent facilitation of calcium influx. Both receptor and non-receptor stimulated calcium influx is substantially attenuated but not completely abolished by inhibition of voltage-gated calcium channels, suggesting that depletion of intracellular calcium pool in these cells provides a signal for both voltage-independent and -dependent calcium influx, the latter by facilitating the pacemaking activity. These cells also express purinergic P2Y1 receptors and their activation by extracellular ATP mimics TRH action on calcium mobilization and influx. The thyroid hormone triiodothyronine prolongs duration of TRH-induced calcium spikes during 30-min exposure. These data indicate that TαT1 cells are capable of responding to natively feed-forward TRH signaling and intrapituitary ATP signaling with acute calcium mobilization and sustained calcium influx. Amplification of TRH-induced calcium signaling by triiodothyronine further suggests the existence of a pathway for positive feedback effects of thyroid hormones probably in a non-genomic manner.
Collapse
Affiliation(s)
- Melanija Tomić
- Section on Cellular Signaling, The Eunice Kennedy Shiver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-4510, United States
| | - Paula Bargi-Souza
- Section on Cellular Signaling, The Eunice Kennedy Shiver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-4510, United States; Department of Physiology and Biophysics of the Institute of Biomedical Sciences, University of São Paulo, SP, Brazil
| | - Elias Leiva-Salcedo
- Section on Cellular Signaling, The Eunice Kennedy Shiver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-4510, United States
| | - Maria Tereza Nunes
- Department of Physiology and Biophysics of the Institute of Biomedical Sciences, University of São Paulo, SP, Brazil
| | - Stanko S Stojilkovic
- Section on Cellular Signaling, The Eunice Kennedy Shiver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-4510, United States.
| |
Collapse
|
11
|
Xie H, Hoffmann HM, Meadows JD, Mayo SL, Trang C, Leming SS, Maruggi C, Davis SW, Larder R, Mellon PL. Homeodomain Proteins SIX3 and SIX6 Regulate Gonadotrope-specific Genes During Pituitary Development. Mol Endocrinol 2015; 29:842-55. [PMID: 25915183 PMCID: PMC4447639 DOI: 10.1210/me.2014-1279] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 04/20/2015] [Indexed: 12/15/2022] Open
Abstract
Sine oculis-related homeobox 3 (SIX3) and SIX6, 2 closely related homeodomain transcription factors, are involved in development of the mammalian neuroendocrine system and mutations of Six6 adversely affect fertility in mice. We show that both small interfering RNA knockdown in gonadotrope cell lines and knockout of Six6 in both embryonic and adult male mice (Six6 knockout) support roles for SIX3 and SIX6 in transcriptional regulation in gonadotrope gene expression and that SIX3 and SIX6 can functionally compensate for each other. Six3 and Six6 expression patterns in gonadotrope cell lines reflect the timing of the expression of pituitary markers they regulate. Six3 is expressed in an immature gonadotrope cell line and represses transcription of the early lineage-specific pituitary genes, GnRH receptor (GnRHR) and the common α-subunit (Cga), whereas Six6 is expressed in a mature gonadotrope cell line and represses the specific β-subunits of LH and FSH (LHb and FSHb) that are expressed later in development. We show that SIX6 repression requires interaction with transducin-like enhancer of split corepressor proteins and competition for DNA-binding sites with the transcriptional activator pituitary homeobox 1. Our studies also suggest that estradiol and circadian rhythm regulate pituitary expression of Six6 and Six3 in adult females but not in males. In summary, SIX3 and SIX6 play distinct but compensatory roles in regulating transcription of gonadotrope-specific genes as gonadotrope cells differentiate.
Collapse
Affiliation(s)
- Huimin Xie
- Department of Reproductive Medicine and the Center for Reproductive Science and Medicine (H.X., H.M.H., J.D.M., S.L.M., C.T., S.S.L., C.M., R.L., P.L.M.), University of California, San Diego, La Jolla, California 92093; and Department of Human Genetics (S.W.D.), University of Michigan, Ann Arbor, Michigan 48109
| | - Hanne M Hoffmann
- Department of Reproductive Medicine and the Center for Reproductive Science and Medicine (H.X., H.M.H., J.D.M., S.L.M., C.T., S.S.L., C.M., R.L., P.L.M.), University of California, San Diego, La Jolla, California 92093; and Department of Human Genetics (S.W.D.), University of Michigan, Ann Arbor, Michigan 48109
| | - Jason D Meadows
- Department of Reproductive Medicine and the Center for Reproductive Science and Medicine (H.X., H.M.H., J.D.M., S.L.M., C.T., S.S.L., C.M., R.L., P.L.M.), University of California, San Diego, La Jolla, California 92093; and Department of Human Genetics (S.W.D.), University of Michigan, Ann Arbor, Michigan 48109
| | - Susan L Mayo
- Department of Reproductive Medicine and the Center for Reproductive Science and Medicine (H.X., H.M.H., J.D.M., S.L.M., C.T., S.S.L., C.M., R.L., P.L.M.), University of California, San Diego, La Jolla, California 92093; and Department of Human Genetics (S.W.D.), University of Michigan, Ann Arbor, Michigan 48109
| | - Crystal Trang
- Department of Reproductive Medicine and the Center for Reproductive Science and Medicine (H.X., H.M.H., J.D.M., S.L.M., C.T., S.S.L., C.M., R.L., P.L.M.), University of California, San Diego, La Jolla, California 92093; and Department of Human Genetics (S.W.D.), University of Michigan, Ann Arbor, Michigan 48109
| | - Sunamita S Leming
- Department of Reproductive Medicine and the Center for Reproductive Science and Medicine (H.X., H.M.H., J.D.M., S.L.M., C.T., S.S.L., C.M., R.L., P.L.M.), University of California, San Diego, La Jolla, California 92093; and Department of Human Genetics (S.W.D.), University of Michigan, Ann Arbor, Michigan 48109
| | - Chiara Maruggi
- Department of Reproductive Medicine and the Center for Reproductive Science and Medicine (H.X., H.M.H., J.D.M., S.L.M., C.T., S.S.L., C.M., R.L., P.L.M.), University of California, San Diego, La Jolla, California 92093; and Department of Human Genetics (S.W.D.), University of Michigan, Ann Arbor, Michigan 48109
| | - Shannon W Davis
- Department of Reproductive Medicine and the Center for Reproductive Science and Medicine (H.X., H.M.H., J.D.M., S.L.M., C.T., S.S.L., C.M., R.L., P.L.M.), University of California, San Diego, La Jolla, California 92093; and Department of Human Genetics (S.W.D.), University of Michigan, Ann Arbor, Michigan 48109
| | - Rachel Larder
- Department of Reproductive Medicine and the Center for Reproductive Science and Medicine (H.X., H.M.H., J.D.M., S.L.M., C.T., S.S.L., C.M., R.L., P.L.M.), University of California, San Diego, La Jolla, California 92093; and Department of Human Genetics (S.W.D.), University of Michigan, Ann Arbor, Michigan 48109
| | - Pamela L Mellon
- Department of Reproductive Medicine and the Center for Reproductive Science and Medicine (H.X., H.M.H., J.D.M., S.L.M., C.T., S.S.L., C.M., R.L., P.L.M.), University of California, San Diego, La Jolla, California 92093; and Department of Human Genetics (S.W.D.), University of Michigan, Ann Arbor, Michigan 48109
| |
Collapse
|
12
|
Kim S, Jung J, Lee I, Jung D, Youn H, Choi K. Thyroid disruption by triphenyl phosphate, an organophosphate flame retardant, in zebrafish (Danio rerio) embryos/larvae, and in GH3 and FRTL-5 cell lines. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2015; 160:188-96. [PMID: 25646720 DOI: 10.1016/j.aquatox.2015.01.016] [Citation(s) in RCA: 150] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 01/19/2015] [Accepted: 01/21/2015] [Indexed: 05/03/2023]
Abstract
Triphenyl phosphate (TPP), one of the most widely used organophosphate flame retardants (OPFRs), has frequently been detected in the environment and biota. However, knowledge of its toxicological effects is limited. The present study was conducted to determine the adverse effects of TPP on the thyroid endocrine system of embryonic/larval zebrafish, and the underlying mechanisms for these effects were studied using rat pituitary (GH3) and thyroid follicular (FRTL-5) cell lines. In the GH3 cells, TPP up-regulated the expression of the tshβ, trα, and trβ genes, while T3, a positive control, down-regulated the expression of these genes. In the FRTL-5 cells, the expression of the nis and tpo genes was significantly up-regulated, suggesting that TPP stimulates thyroid hormone synthesis in the thyroid gland. In zebrafish larvae at 7 days post-fertilization (dpf), TPP exposure led to significant increases in both T3 and T4 concentrations and expression of the genes involved in thyroid hormone synthesis. Exposure to TPP also significantly up-regulated the expression of the genes related to the metabolism (dio1), transport (ttr), and elimination (ugt1ab) of thyroid hormones. The down-regulation of the crh and tshβ genes in the zebrafish larvae suggests the activation of a central regulatory feedback mechanism induced by the increased T3 levels in vivo. Taken together, our observations show that TPP could increase the thyroid hormone concentrations in the early life stages of zebrafish by disrupting the central regulation and hormone synthesis pathways.
Collapse
Affiliation(s)
- Sujin Kim
- School of Public Health, Seoul National University, Seoul 151-742, Republic of Korea
| | - Joeun Jung
- School of Public Health, Seoul National University, Seoul 151-742, Republic of Korea
| | - Inae Lee
- School of Public Health, Seoul National University, Seoul 151-742, Republic of Korea
| | - Dawoon Jung
- School of Public Health, Seoul National University, Seoul 151-742, Republic of Korea
| | - Hyewon Youn
- Department of Nuclear Medicine, Cancer Imaging Center, Seoul National University Hospital, 110-744, Republic of Korea; Tumor Microenvironment Global Core Research Center, Cancer Research Institute, College of Medicine, Seoul National University, 110-799, Republic of Korea
| | - Kyungho Choi
- School of Public Health, Seoul National University, Seoul 151-742, Republic of Korea.
| |
Collapse
|
13
|
Bargi-Souza P, Kucka M, Bjelobaba I, Tomić M, Janjic MM, Nunes MT, Stojilkovic SS. Loss of basal and TRH-stimulated Tshb expression in dispersed pituitary cells. Endocrinology 2015; 156:242-54. [PMID: 25356823 PMCID: PMC4272397 DOI: 10.1210/en.2014-1281] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
This study addresses the in vivo and in vitro expression pattern of three genes that are operative in the thyrotroph subpopulation of anterior pituitary cells: glycoprotein α-chain (Cga), thyroid-stimulating hormone β-chain (Tshb), and TRH receptor (Trhr). In vivo, the expression of Cga and Tshb was robust, whereas the expression of Trhr was low. In cultured pituitary cells, there was a progressive decline in the expression of Cga, Tshb, and Trhr. The expression of Tshb could not be reversed via pulsatile or continuous TRH application in variable concentrations and treatment duration or by the removal of thyroid and steroid hormones from the sera. In parallel, the expression of CGA and TSHB proteins declined progressively in pituitary cells from both sexes. The lack of the effect of TRH on Tshb expression was not related to the age of pituitary cultures and the presence of functional TRH receptors. In cultured pituitary fragments, there was also a rapid decline in expression of these genes, but TRH was able to induce transient Tshb expression. In vivo, thyrotrophs were often in close proximity to each other and to somatotroph and folliculostellate cell networks and especially to the lactotroph cell network; such an organization pattern was lost in vitro. These observations suggest that the lack of influence of anterior pituitary architecture and/or intrapituitary factors probably accounts for the loss of basal and TRH-stimulated Tshb expression in dispersed pituitary cells.
Collapse
Affiliation(s)
- Paula Bargi-Souza
- Section on Cellular Signaling (P.B.-S., M.K., I.B., M.T., M.M.J., S.S.S.), The Eunice Kennedy Shiver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4510; and Department of Physiology and Biophysics (P.B.-S., M.T.N.), Institute of Biomedical Sciences, University of São Paulo, 05508-000 São Paulo, SP, Brazil
| | | | | | | | | | | | | |
Collapse
|
14
|
Aninye IO, Matsumoto S, Sidhaye AR, Wondisford FE. Circadian regulation of Tshb gene expression by Rev-Erbα (NR1D1) and nuclear corepressor 1 (NCOR1). J Biol Chem 2014; 289:17070-7. [PMID: 24794873 DOI: 10.1074/jbc.m114.569723] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Thyroid hormones (TH) are critical for development, growth, and metabolism. Circulating TH levels are tightly regulated by thyroid-stimulating hormone (TSH) secretion within the hypothalamic-pituitary-thyroid axis. Although circadian TSH secretion has been well documented, the mechanism of this observation remains unclear. Recently, the nuclear corepressor, NCOR1, has been postulated to regulate TSH expression, presumably by interacting with thyroid hormone receptors (THRs) bound to TSH subunit genes. We report herein the first in vitro study of NCOR1 regulation of TSH in a physiologically relevant cell system, the TαT1.1 mouse thyrotroph cell line. Knockdown of NCOR1 by shRNA adenovirus increased baseline Tshb mRNA levels compared with scrambled control, but surprisingly had no affect on the T3-mediated repression of this gene. Using ChIP, we show that NCOR1 enriches on the Tshb promoter at sites different from THR previously identified by our group. Furthermore, NCOR1 enrichment on Tshb is unaffected by T3 treatment. Given that NCOR1 does not target THR on Tshb, we hypothesized that NCOR1 targeted Rev-Erbα (NR1D1), an orphan nuclear receptor that is a potent repressor of gene transcription and regulator of metabolism and circadian rhythms. Using a serum shock technique, we synchronized TαT1.1 cells to study circadian gene expression. Post-synchronization, Tshb and Nr1d1 mRNA levels displayed oscillations that inversely correlated with each other. Furthermore, NR1D1 was enriched at the same locus as NCOR1 on Tshb. Therefore, we propose a model for Tshb regulation whereby NR1D1 and NCOR1 interact to regulate circadian expression of Tshb independent of TH negative regulation.
Collapse
Affiliation(s)
- Irene O Aninye
- From the Division of Metabolism, Departments of Pediatrics, Physiology, and Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287
| | - Shunichi Matsumoto
- From the Division of Metabolism, Departments of Pediatrics, Physiology, and Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287
| | - Aniket R Sidhaye
- From the Division of Metabolism, Departments of Pediatrics, Physiology, and Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287
| | - Fredric E Wondisford
- From the Division of Metabolism, Departments of Pediatrics, Physiology, and Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287
| |
Collapse
|
15
|
Rijntjes E, Scholz PM, Mugesh G, Köhrle J. Se- and s-based thiouracil and methimazole analogues exert different inhibitory mechanisms on type 1 and type 2 deiodinases. Eur Thyroid J 2013; 2:252-8. [PMID: 24783056 PMCID: PMC3923599 DOI: 10.1159/000355288] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 08/20/2013] [Indexed: 11/19/2022] Open
Abstract
The thioamide anti-thyroid drugs methimazole (MMI) and propylthiouracil (PTU) play a pivotal role in the treatment of hyperthyroidism. MMI exerts its effect via inhibiting one of the key enzymes involved in synthesis of thyroid hormones (TH), thyroid peroxidase (TPO). PTU is both an inhibitor of TPO and type 1 deiodinase (D1), which catalyzes TH deiodination at both aromatic rings. In contrast, no selective inhibitors are known for type 2 deiodinase (D2) or type 3 deiodinase, which deiodinate TH at the phenolic or tyrosyl ring, respectively. We aimed to identify specific inhibitors for D1 or D2. New Se- and S-based PTU and MMI-like compounds have been generated. The D1 and D2 inhibiting capacity of several compounds was tested in vitro. Our data show that compounds based on a PTU and MMI backbone can differentially influence the reaction kinetics of deiodinases. For inhibition of D1, the addition of a phenyl group to the PTU backbone increases potency by at least 10-fold over PTU. For inhibition of D2, the addition of an aromatic ring structure to MMI and its Se isomer increases inhibitory potency by an order of magnitude. Furthermore, S-methylation of the MMI changes its reaction kinetics from non-competitive to uncompetitive with respect to the cofactor dithiothreitol. These results open perspectives for further investigations on identifying specific inhibitors of the deiodinase isoenzymes, potentially based on the addition of aromatic ring structures or alkyl groups to PTU and MMI.
Collapse
Affiliation(s)
- Eddy Rijntjes
- Institut für Experimentelle Endokrinologie, Charité-Universtätsmedizin Berlin, Berlin, Germany
| | - Philip Moritz Scholz
- Institut für Experimentelle Endokrinologie, Charité-Universtätsmedizin Berlin, Berlin, Germany
| | - Govindasamy Mugesh
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, India
| | - Josef Köhrle
- Institut für Experimentelle Endokrinologie, Charité-Universtätsmedizin Berlin, Berlin, Germany
| |
Collapse
|
16
|
The CpG island in the murine foxl2 proximal promoter is differentially methylated in primary and immortalized cells. PLoS One 2013; 8:e76642. [PMID: 24098544 PMCID: PMC3788739 DOI: 10.1371/journal.pone.0076642] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 08/30/2013] [Indexed: 11/23/2022] Open
Abstract
Forkhead box L2 (Foxl2), a member of the forkhead transcription factor family, plays important roles in pituitary follicle-stimulating hormone synthesis and in ovarian maintenance and function. Mutations in the human FOXL2 gene cause eyelid malformations and premature ovarian failure. FOXL2/Foxl2 is expressed in pituitary gonadotrope and thyrotrope cells, the perioptic mesenchyme of the developing eyelid, and ovarian granulosa cells. The mechanisms governing this cell-restricted expression have not been described. We mapped the Foxl2 transcriptional start site in immortalized murine gonadotrope-like cells, LβT2, by 5’ rapid amplification of cDNA ends and then PCR amplified approximately 1 kb of 5’ flanking sequence from murine genomic DNA. When ligated into a reporter plasmid, the proximal promoter conferred luciferase activity in both homologous (LβT2) and, unexpectedly, heterologous (NIH3T3) cells. In silico analyses identified a CpG island in the proximal promoter and 5’ untranslated region, suggesting that Foxl2 transcription might be regulated epigenetically. Indeed, pyrosequencing and quantitative analysis of DNA methylation using real-time PCR revealed Foxl2 proximal promoter hypomethylation in homologous compared to some, though not all, heterologous cell lines. The promoter was also hypomethylated in purified murine gonadotropes. In vitro promoter methylation completely silenced reporter activity in heterologous and homologous cells. Collectively, the data suggest that differential proximal promoter DNA methylation may contribute to cell-specific Foxl2 expression in some cellular contexts. However, gonadotrope-specific expression of the gene cannot be explained by promoter hypomethylation alone.
Collapse
|
17
|
Xie H, Cherrington BD, Meadows JD, Witham EA, Mellon PL. Msx1 homeodomain protein represses the αGSU and GnRH receptor genes during gonadotrope development. Mol Endocrinol 2013; 27:422-36. [PMID: 23371388 DOI: 10.1210/me.2012-1289] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Multiple homeodomain transcription factors are crucial for pituitary organogenesis and cellular differentiation. A homeodomain repressor, Msx1, is expressed from the ventral aspect of the developing anterior pituitary and implicated in gonadotrope differentiation. Here, we find that Msx1 represses transcription of lineage-specific pituitary genes such as the common α-glycoprotein subunit (αGSU) and GnRH receptor (GnRHR) promoters in the mouse gonadotrope-derived cell lines, αT3-1 and LβT2. Repression of the mouse GnRHR promoter by Msx1 is mediated through a consensus-binding motif in the downstream activin regulatory element (DARE). Truncation and mutation analyses of the human αGSU promoter map Msx1 repression to a site at -114, located at the junctional regulatory element (JRE). Dlx activators are closely related to the Msx repressors, acting through the same elements, and Dlx3 and Dlx2 act as transcriptional activators for GnRHR and αGSU, respectively. Small interfering RNA knockdown of Msx1 in αT3-1 cells increases endogenous αGSU and GnRHR mRNA expression. Msx1 gene expression reaches its maximal expression at the rostral edge at e13.5. The subsequent decline in Msx1 expression specifically coincides with the onset of expression of both αGSU and GnRHR. The expression levels of both αGSU and GnRHR in Msx1-null mice at e18.5 are higher compared with wild type, further confirming a role for Msx1 in the repression of αGSU and GnRHR. In summary, Msx1 functions as a negative regulator early in pituitary development by repressing the gonadotrope-specific αGSU and GnRHR genes, but a temporal decline in Msx1 expression alleviates this repression allowing induction of GnRHR and αGSU, thus serving to time the onset of gonadotrope-specific gene program.
Collapse
Affiliation(s)
- Huimin Xie
- Department of Reproductive Medicine, Center for Reproductive Science and Medicine, University of California San Diego, La Jolla, CA 92093-0674, USA
| | | | | | | | | |
Collapse
|
18
|
Wege N, Schutkowski A, König B, Brandsch C, Weiwad M, Stangl GI. PPARα modulates the TSH β-subunit mRNA expression in thyrotrope TαT1 cells and in a mouse model. Mol Nutr Food Res 2012; 57:376-89. [PMID: 23255496 DOI: 10.1002/mnfr.201200409] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Revised: 09/23/2012] [Accepted: 10/30/2012] [Indexed: 11/07/2022]
Abstract
SCOPE Fasting leads to a significant downregulation of the hypothalamus-pituitary-thyroid axis, and peroxisome proliferator-activated receptor (PPAR) α is a key transcription factor in mediating a magnitude of adaptive responses to fasting. In this study, we examined the role of PPARα in regulation of the hypothalamus-pituitary-thyroid axis. METHODS AND RESULTS Thyroid-stimulating hormone β-subunit (TSHβ) mRNA abundance was being reduced in response to treatment of TαT1 cells with PPARα agonists (p < 0.05), indicating an inhibitory transcriptional regulation of TSHβ by PPARα. As expected, fasting significantly downregulated TSHβ mRNA expression in a two-factorial study with fed or fasted wild-type (WT) and PPARα knockout mice (p < 0.05). In contrast to the in vitro data, fasted PPARα knockout mice revealed lower mRNA concentrations of pituitary TSHβ (-64%) and TSH-regulated thyroid genes, and lower plasma concentrations of thyroxine (T4, -25%), triiodothyronine (T3, -25%), free T4 (-60%), and free T3 (-35%) than fasted WT mice (p < 0.05). Those differences were not observed in fed mice. CONCLUSIONS Data from thyrotrope cells revealed that PPARα could contribute to the fasting-associated downregulation of the TSHβ mRNA expression. In a mouse model, fasting led to a significant reduction in TSHβ mRNA level, but unexpectedly this effect was stronger in mice lacking PPARα than in WT mice.
Collapse
Affiliation(s)
- Nicole Wege
- Institute of Agricultural and Nutritional Sciences, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | | | | | | | | | | |
Collapse
|
19
|
Chiamolera MI, Sidhaye AR, Matsumoto S, He Q, Hashimoto K, Ortiga-Carvalho TM, Wondisford FE. Fundamentally distinct roles of thyroid hormone receptor isoforms in a thyrotroph cell line are due to differential DNA binding. Mol Endocrinol 2012; 26:926-39. [PMID: 22570333 DOI: 10.1210/me.2011-1290] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Thyroid hormones have a profound influence on human development and disease. The hypothalamic-pituitary-thyroid axis involves finely tuned feedback mechanisms to maintain thyroid hormone (TH) levels. Despite the important role of TH-negative feedback in regulating this axis, the mechanism by which this occurs is not clearly defined. Previous in vivo studies suggest separate roles for the two thyroid hormone receptor isoforms, THRA and THRB, in this axis. We performed studies using a unique pituitary thyrotroph cell line (TαT1.1) to determine the relative roles of THRA and THRB in the regulation of Tshb. Using chromatin immunoprecipitation assays, we found that THRB, not THRA, bound to the Tshb promoter. By selectively depleting THRB, THRA, or both THRA and THRB in TαT1.1 cells, we found that simultaneous knockdown of both THRB and THRA abolished T(3)-mediated down-regulation of Tshb at concentrations as high as 100 nm T(3). In contrast, THRA knockdown alone had no effect on T(3)-negative regulation, whereas THRB knockdown alone abolished T(3)-mediated down-regulation of Tshb mRNA levels at 10 nm but not 100 nm T(3) concentrations. Interestingly, chromatin immunoprecipitation assays showed that THRA becomes enriched on the Tshb promoter after knockdown of THRB. Thus, a likely mechanism for the differential effects of THR isoforms on Tshb may be based on their differential DNA-binding affinity to the promoter.
Collapse
|
20
|
Janssen JS, Sharma V, Pugazhenthi U, Sladek C, Wood WM, Haugen BR. A rexinoid antagonist increases the hypothalamic-pituitary-thyroid set point in mice and thyrotrope cells. Mol Cell Endocrinol 2011; 339:1-6. [PMID: 21458528 PMCID: PMC3112467 DOI: 10.1016/j.mce.2011.03.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 12/17/2010] [Accepted: 03/02/2011] [Indexed: 11/25/2022]
Abstract
Retinoid X receptor (RXR) signaling influences thyrotrope function. Synthetic RXR agonists, rexinoids, can cause central hypothyroidism. To test the hypothesis that endogenous rexinoids contribute to the TSH 'set point', TαT1 mouse thyrotrope cells were treated with a rexinoid antagonist, LG101208. Increasing concentrations of LG101208 significantly increased TSHβ mRNA levels, indicating that the rexinoid antagonist may interfere with RXR-signaling by an endogenous rexinoid in thyrotropes. When the same experiments were repeated in the presence of charcoal-stripped serum the effect of the rexinoid antagonist was lost. Pretreatment with the transcription inhibitor DRB blocked the increase of TSHβ mRNA levels by rexinoid antagonist, indicating the primary effect is at the level of gene transcription. Mice treated with LG101208 had higher levels of serum T4, T4/TSH ratios as well as pituitary α-subunit and TSHβ mRNA compared with vehicle treated mice. Hypothalamic TRH levels were unchanged. In summary, the rexinoid antagonist, LG101208, increases TSH subunit mRNA levels in thyrotrope cells and mouse pituitaries, primarily at the level of gene transcription. These data suggest that an "endogenous rexinoid" contributes to the TSH 'set point' in thyrotropes.
Collapse
Affiliation(s)
- Jennifer S. Janssen
- Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado Denver, School of Medicine, Aurora, Colorado
| | - Vibha Sharma
- Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado Denver, School of Medicine, Aurora, Colorado
| | - Umarani Pugazhenthi
- Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado Denver, School of Medicine, Aurora, Colorado
| | - Celia Sladek
- Department of Physiology, University of Colorado Denver, School of Medicine, Aurora, Colorado
| | - William M. Wood
- Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado Denver, School of Medicine, Aurora, Colorado
- University of Colorado Cancer Center, University of Colorado Denver, School of Medicine, Aurora, Colorado
| | - Bryan R. Haugen
- Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado Denver, School of Medicine, Aurora, Colorado
- University of Colorado Cancer Center, University of Colorado Denver, School of Medicine, Aurora, Colorado
| |
Collapse
|
21
|
Lellis-Santos C, Giannocco G, Nunes MT. The case of thyroid hormones: how to learn physiology by solving a detective case. ADVANCES IN PHYSIOLOGY EDUCATION 2011; 35:219-226. [PMID: 21652508 DOI: 10.1152/advan.00135.2010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Thyroid diseases are prevalent among endocrine disorders, and careful evaluation of patients' symptoms is a very important part in their diagnosis. Developing new pedagogical strategies, such as problem-based learning (PBL), is extremely important to stimulate and encourage medical and biomedical students to learn thyroid physiology and identify the signs and symptoms of thyroid dysfunction. The present study aimed to create a new pedagogical approach to build deep knowledge about hypo-/hyperthyroidism by proposing a hands-on activity based on a detective case, using alternative materials in place of laboratory animals. After receiving a description of a criminal story involving changes in thyroid hormone economy, students collected data from clues, such as body weight, mesenteric vascularization, visceral fat, heart and thyroid size, heart rate, and thyroid-stimulating hormone serum concentration to solve the case. Nevertheless, there was one missing clue for each panel of data. Four different materials were proposed to perform the same practical lesson. Animals, pictures, small stuffed toy rats, and illustrations were all effective to promote learning, and the detective case context was considered by students as inviting and stimulating. The activity can be easily performed independently of the institution's purchasing power. The practical lesson stimulated the scientific method of data collection and organization, discussion, and review of thyroid hormone actions to solve the case. Hence, this activity provides a new strategy and alternative materials to teach without animal euthanization.
Collapse
Affiliation(s)
- Camilo Lellis-Santos
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, Brazil
| | | | | |
Collapse
|
22
|
Ohba K, Sasaki S, Matsushita A, Iwaki H, Matsunaga H, Suzuki S, Ishizuka K, Misawa H, Oki Y, Nakamura H. GATA2 mediates thyrotropin-releasing hormone-induced transcriptional activation of the thyrotropin β gene. PLoS One 2011; 6:e18667. [PMID: 21533184 PMCID: PMC3077393 DOI: 10.1371/journal.pone.0018667] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Accepted: 03/08/2011] [Indexed: 11/19/2022] Open
Abstract
Thyrotropin-releasing hormone (TRH) activates not only the secretion of thyrotropin (TSH) but also the transcription of TSHβ and α-glycoprotein (αGSU) subunit genes. TSHβ expression is maintained by two transcription factors, Pit1 and GATA2, and is negatively regulated by thyroid hormone (T3). Our prior studies suggest that the main activator of the TSHβ gene is GATA2, not Pit1 or unliganded T3 receptor (TR). In previous studies on the mechanism of TRH-induced activation of the TSHβ gene, the involvements of Pit1 and TR have been investigated, but the role of GATA2 has not been clarified. Using kidney-derived CV1 cells and pituitary-derived GH3 and TαT1 cells, we demonstrate here that TRH signaling enhances GATA2-dependent activation of the TSHβ promoter and that TRH-induced activity is abolished by amino acid substitution in the GATA2-Zn finger domain or mutation of GATA-responsive element in the TSHβ gene. In CV1 cells transfected with TRH receptor expression plasmid, GATA2-dependent transactivation of αGSU and endothelin-1 promoters was enhanced by TRH. In the gel shift assay, TRH signal potentiated the DNA-binding capacity of GATA2. While inhibition by T3 is dominant over TRH-induced activation, unliganded TR or the putative negative T3-responsive element are not required for TRH-induced stimulation. Studies using GH3 cells showed that TRH-induced activity of the TSHβ promoter depends on protein kinase C but not the mitogen-activated protein kinase, suggesting that the signaling pathway is different from that in the prolactin gene. These results indicate that GATA2 is the principal mediator of the TRH signaling pathway in TSHβ expression.
Collapse
Affiliation(s)
- Kenji Ohba
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Shigekazu Sasaki
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
- * E-mail:
| | - Akio Matsushita
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Hiroyuki Iwaki
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Hideyuki Matsunaga
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Shingo Suzuki
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Keiko Ishizuka
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Hiroko Misawa
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Yutaka Oki
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Hirotoshi Nakamura
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| |
Collapse
|
23
|
Goulart-Silva F, de Souza PB, Nunes MT. T3 rapidly modulates TSHβ mRNA stability and translational rate in the pituitary of hypothyroid rats. Mol Cell Endocrinol 2011; 332:277-82. [PMID: 21078364 DOI: 10.1016/j.mce.2010.11.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Accepted: 11/03/2010] [Indexed: 10/18/2022]
Abstract
Whereas it is well known that T3 inhibits TSHβ gene transcription, its effects on TSHβ mRNA stability and translation have been poorly investigated. This study examined these possibilities, by evaluating the TSHβ transcripts poly(A) tail length, translational rate and binding to cytoskeleton, in pituitaries of thyroidectomized and sham-operated rats treated with T3 or saline, and killed 30 min thereafter. The hypothyroidism induced an increase of TSHβ transcript poly(A) tail, as well as of its content in ribosomes and attachment to cytoskeleton. The hypothyroid rats acutely treated with T3 exhibited a reduction of TSHβ mRNA poly(A) tail length and recruitment to ribosomes, indicating that this treatment decreased the stability and translation rate of TSHβ mRNA. Nevertheless, acute T3 administration to sham-operated rats provoked an increase of TSHβ transcripts binding to ribosomes. These data add new insight to an important role of T3 in rapidly regulating TSH gene expression at posttranscriptional level.
Collapse
Affiliation(s)
- Francemilson Goulart-Silva
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, 05508-900 São Paulo, Brazil
| | | | | |
Collapse
|
24
|
Rosene ML, Wittmann G, Arrojo e Drigo R, Singru PS, Lechan RM, Bianco AC. Inhibition of the type 2 iodothyronine deiodinase underlies the elevated plasma TSH associated with amiodarone treatment. Endocrinology 2010; 151:5961-70. [PMID: 20926587 PMCID: PMC2999495 DOI: 10.1210/en.2010-0553] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Accepted: 09/07/2010] [Indexed: 01/10/2023]
Abstract
The widely prescribed cardiac antiarrhythmic drug amiodarone (AMIO) and its main metabolite, desethylamiodarone (DEA), have multiple side effects on thyroid economy, including an elevation in serum TSH levels. To study the AMIO effect on TSH, mice with targeted disruption of the type 2 deiodinase gene (D2KO) were treated with 80 mg/kg AMIO for 4 wk. Only wild-type (WT) mice controls developed the expected approximate twofold rise in plasma TSH, illustrating a critical role for D2 in this mechanism. A disruption in the D2 pathway caused by AMIO could interfere with the transduction of the T4 signal, generating less T3 and softening the TSH feedback mechanism. When added directly to sonicates of HEK-293 cells transiently expressing D2, both AMIO and DEA behaved as noncompetitive inhibitors of D2 [IC(50) of >100 μm and ∼5 μm, respectively]. Accordingly, D2 activity was significantly decreased in the median eminence and anterior pituitary sonicates of AMIO-treated mice. However, the underlying effect on TSH is likely to be at the pituitary gland given that in AMIO-treated mice the paraventricular TRH mRNA levels (which are negatively regulated by D2-generated T3) were decreased. In contrast, AMIO and DEA both exhibited dose-dependent inhibition of D2 activity and elevation of TSH secretion in intact TαT1 cells, a pituitary thyrotroph cell line used to model the TSH feedback mechanism. In conclusion, AMIO and DEA are noncompetitive inhibitors of D2, with DEA being much more potent, and this inhibition at the level of the pituitary gland contributes to the rise in TSH seen in patients taking AMIO.
Collapse
Affiliation(s)
- Matthew L Rosene
- Division of Endocrinology, Diabetes, and Metabolism, University of Miami Miller School of Medicine, Miami, Florida 33136, USA
| | | | | | | | | | | |
Collapse
|
25
|
Kim KK, Park KS, Song SB, Kim KE. Insulin represses transcription of the thyroid stimulating hormone beta-subunit gene through increased recruitment of nuclear factor I. J Biol Chem 2010; 285:32003-11. [PMID: 20685655 DOI: 10.1074/jbc.m110.107573] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Although the regulation of thyroid stimulating hormone β-subunit gene (TSHβ) has been intensively studied, the functions of transcription factors involved are not fully understood. The authors found that the -615/-516 promoter region of the TSHβ interacts specifically with nuclear proteins derived from pituitary tissue or from cultured thyrotroph cells. The actual binding site at the nucleotide level, as revealed by DNase I protection assay, includes the consensus sequence for nuclear factor I (NFI). RT-PCR analysis indicated that NFI-B expression is restricted to thyrotroph cells in the anterior pituitary. EMSA and ChIP analysis showed that NFI-B binds most efficiently to the -588/-560 region of TSHβ promoter. The forced expressions of NFI-B markedly reduced TSHβ promoter activity and its mRNA expression. Furthermore, it was also shown that the -588/-560 region is involved in the insulin-mediated repression of the TSHβ. It was of particular interest to observe that NFI-B was recruited to the -588/-560 region of the TSHβ promoter in an insulin-dependent manner. Taken together, this study provides new insights of the delicate regulations of energy metabolism and hormonal homeostasis.
Collapse
Affiliation(s)
- Kee Kwang Kim
- Department of Biochemistry, College of Natural Sciences, Chungnam National University, Daejeon 305-764, Republic of Korea
| | | | | | | |
Collapse
|
26
|
Zatelli MC, Gentilin E, Daffara F, Tagliati F, Reimondo G, Carandina G, Ambrosio MR, Terzolo M, Degli Uberti EC. Therapeutic concentrations of mitotane (o,p'-DDD) inhibit thyrotroph cell viability and TSH expression and secretion in a mouse cell line model. Endocrinology 2010; 151:2453-61. [PMID: 20392828 DOI: 10.1210/en.2009-1404] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Mitotane therapy is associated with many side effects, including thyroid function perturbations mimicking central hypothyroidism, possibly due to laboratory test interference or pituitary direct effects of mitotane. We investigated whether increasing concentrations of mitotane in the therapeutic range might interfere with thyroid hormone assays and evaluated the effects of mitotane on a mouse TSH-producing pituitary cell line. TSH, free T(4), and free T(3) levels do not significantly change in sera from hypo-, hyper-, or euthyroid patients after addition of mitotane at concentrations in the therapeutic window. In the mouse TalphaT1 cell line, mitotane inhibits both TSH expression and secretion, blocks TSH response to TRH, and reduces cell viability, inducing apoptosis at concentrations in the therapeutic window. TRH is not capable of rescuing TalphaT1 cells from the inhibitory effects of mitotane on TSH expression and secretion, which appear after short time treatment and persist over time. Our results demonstrate that mitotane does not interfere with thyroid hormone laboratory tests but directly reduces both secretory activity and cell viability on pituitary TSH-secreting mouse cells. These data represent a possible explanation of the biochemical picture consistent with central hypothyroidism in patients undergoing mitotane therapy and open new perspectives on the direct pituitary effects of this drug.
Collapse
Affiliation(s)
- Maria Chiara Zatelli
- Section of Endocrinology, Department of Biomedical Sciences and Advanced Therapies, University of Ferrara, Via Savonarola 9, 44121 Ferrara, Italy
| | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Jeong KH, Gill JC, Nosé V, Parlow AF, Carroll RS, Kaiser UB. Expression of a gonadotropin-releasing hormone receptor-simian virus 40 T-antigen transgene has sex-specific effects on the reproductive axis. Endocrinology 2009; 150:3383-91. [PMID: 19282386 PMCID: PMC2703545 DOI: 10.1210/en.2008-1362] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The GnRH receptor (GnRHR) responds to pulsatile GnRH signals to coordinate pituitary gonadotropin synthesis and secretion. Previously, a 1.2-kb fragment of the 5'-flanking region isolated from the mouse GnRHR gene was shown to target expression to pituitary gonadotropes in vivo. The 1.2-kb gene promoter fused to the simian virus 40 large T antigen (TAg) was used to generate transgenic mice that form gonadotrope-derived pituitary tumors at 4-5 months of age. Transgenic female mice have hypogonadotropic hypogonadism, infantile gonads, and are infertile throughout their life span, whereas males remain reproductively intact until their tumors become large. We hypothesized that the targeted TAg expression causes a sex-specific disruption of the reproductive axis at the level of the pituitary gland. To test this hypothesis, we characterized the pituitary gonadotropin beta-subunit and TAg expression patterns, and measured plasma gonadotropin and gonadal steroid levels in female and male mice before and after pituitary tumor development. TAg expression was observed in transgenic females and males 15 d of age, before tumor development. Interestingly, and in contrast to the transgenic males, pituitary LH beta and FSH beta subunit protein levels, and plasma LH and FSH levels, were reduced in transgenic females. Reproductive organs in transgenic female mice remained underdeveloped but were normal in transgenic males. We conclude that the expression of the TAg transgene driven by the GnRHR gene promoter results in female-specific infertility due to disruption of gonadotropin production and secretion even before tumor development.
Collapse
Affiliation(s)
- Kyeong-Hoon Jeong
- Harvard Medical School, Brigham and Women's Hospital, Division of Endocrinology, Diabetes and Hypertension, 221 Longwood Avenue, Boston, Massachusetts 02115, USA
| | | | | | | | | | | |
Collapse
|
28
|
Gereben B, Zavacki AM, Ribich S, Kim BW, Huang SA, Simonides WS, Zeöld A, Bianco AC. Cellular and molecular basis of deiodinase-regulated thyroid hormone signaling. Endocr Rev 2008; 29:898-938. [PMID: 18815314 PMCID: PMC2647704 DOI: 10.1210/er.2008-0019] [Citation(s) in RCA: 563] [Impact Index Per Article: 35.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Accepted: 08/15/2008] [Indexed: 02/06/2023]
Abstract
The iodothyronine deiodinases initiate or terminate thyroid hormone action and therefore are critical for the biological effects mediated by thyroid hormone. Over the years, research has focused on their role in preserving serum levels of the biologically active molecule T(3) during iodine deficiency. More recently, a fascinating new role of these enzymes has been unveiled. The activating deiodinase (D2) and the inactivating deiodinase (D3) can locally increase or decrease thyroid hormone signaling in a tissue- and temporal-specific fashion, independent of changes in thyroid hormone serum concentrations. This mechanism is particularly relevant because deiodinase expression can be modulated by a wide variety of endogenous signaling molecules such as sonic hedgehog, nuclear factor-kappaB, growth factors, bile acids, hypoxia-inducible factor-1alpha, as well as a growing number of xenobiotic substances. In light of these findings, it seems clear that deiodinases play a much broader role than once thought, with great ramifications for the control of thyroid hormone signaling during vertebrate development and metamorphosis, as well as injury response, tissue repair, hypothalamic function, and energy homeostasis in adults.
Collapse
Affiliation(s)
- Balázs Gereben
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | | | | | | | | | | | | | | |
Collapse
|
29
|
Kim KK, Song SB, Kang KI, Rhee M, Kim KE. Activation of the thyroid-stimulating hormone beta-subunit gene by LIM homeodomain transcription factor Lhx2. Endocrinology 2007; 148:3468-76. [PMID: 17446187 DOI: 10.1210/en.2006-1088] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Although there is evidence that the LIM homeodomain transcription factor, Lhx2, can stimulate transcription of the glycoprotein hormone alpha-subunit gene, the role of Lhx2 in regulating TSH beta-subunit has not been established. In the present studies, the ability of Lhx2 to regulate transcription of the TSH beta-subunit gene was examined. In the thyrotrope-derived TalphaT1 cell line, Lhx2 expression was found to be induced by treatment with either TRH or cAMP, consistent with the possibility that Lhx2 may play a role in mediating the ability of this signaling pathway to stimulate TSH gene expression. Transient, forced overexpression of Lhx2 stimulated activity of a TSH beta-subunit reporter gene. Deletion studies provided evidence that the -177 to -79 region of the TSH beta-subunit promoter was necessary for stimulation of reporter gene activity by Lhx2. A gel mobility shift assay provided the evidence that Lhx2 can bind to this region of DNA. DNase I footprinting studies demonstrated that two distinct regions of the TSHbeta promoter, -118 to -108 and -86 to -68, are protected by Lhx2 from nuclease digestion. These regions contain repeats of the sequence, 5'-(G/T)CAAT(T/A)-3'. Mutation of this sequence, especially in the -86 to -68 region, substantially decreased Lhx2 responsiveness of the TSH beta-subunit reporter gene. In addition, a DNA fragment containing the -177 to -79 region of the TSHbeta promoter was found to confer Lhx2 responsiveness to a minimal promoter. These results provide multiple lines of evidence consistent with a role for Lhx2 in modulating expression of the TSH beta-subunit gene.
Collapse
Affiliation(s)
- Kee K Kim
- Department of Biochemistry, Institute of Biotechnology, Chungnam National University, Daejeon 305-764, Korea
| | | | | | | | | |
Collapse
|
30
|
Matsushita A, Sasaki S, Kashiwabara Y, Nagayama K, Ohba K, Iwaki H, Misawa H, Ishizuka K, Nakamura H. Essential role of GATA2 in the negative regulation of thyrotropin beta gene by thyroid hormone and its receptors. Mol Endocrinol 2007; 21:865-84. [PMID: 17244762 DOI: 10.1210/me.2006-0208] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Previously we reported that the negative regulation of the TSHbeta gene by T(3) and its receptor [thyroid hormone receptor (TR)] is observed in CV1 cells when GATA2 and Pit1 are introduced. Using this system, we further studied the mechanism of TSHbeta inhibition. The negative regulatory element (NRE), which had been reported to mediate T(3)-bound TR (T(3)-TR)-dependent inhibition, is dispensable, because deletion or mutation of NRE did not impair suppression. The reporter construct, TSHbeta-D4-chloramphenicol acetyltransferase, which possesses only the binding sites for Pit1 and GATA2, was activated by GATA2 alone, and this transactivation was specifically inhibited by T(3)-TR. The Zn finger region of GATA2 interacts with the DNA-binding domain of TR in a T(3)-independent manner. The suppression by T(3)-TR was impaired by overexpression of a dominant-negative type TR-associated protein (TRAP) 220, an N- and C-terminal deletion construct, indicating the participation of TRAP220. Chromatin immunoprecipitation assays with a thyrotroph cell line, TalphaT1, revealed that T(3) treatment recruited histone deacetylase 3, reduced the acetylation of histone H4, and caused the dissociation of TRAP220 within 15-30 min. The reduction of histone H4 acetylation was transient, whereas the dissociation of TRAP220 persisted for a longer period. In the negative regulation of the TSHbeta gene by T(3)-TR we report that 1) GATA2 is the major transcriptional activator of the TSHbeta gene, 2) the putative NRE previously reported is not required, 3) TR-DNA-binding domain directly interacts with the Zn finger region of GATA2, and 4) histone deacetylation and TRAP220 dissociation are important.
Collapse
Affiliation(s)
- Akio Matsushita
- Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, Shizuoka 431-3192, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Christoffolete MA, Ribeiro R, Singru P, Fekete C, da Silva WS, Gordon DF, Huang SA, Crescenzi A, Harney JW, Ridgway EC, Larsen PR, Lechan RM, Bianco AC. Atypical expression of type 2 iodothyronine deiodinase in thyrotrophs explains the thyroxine-mediated pituitary thyrotropin feedback mechanism. Endocrinology 2006; 147:1735-43. [PMID: 16396983 DOI: 10.1210/en.2005-1300] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
T(4), the main product of thyroid secretion, is a critical signal in plasma that mediates the TSH-negative feedback mechanism. As a prohormone, T(4) must be converted to T(3) to acquire biological activity; thus, type 2 iodothyronine deiodinase (D2) is expected to play a critical role in this feedback mechanism. However, the mechanistic details of this pathway are still missing because, counterintuitively, D2 activity is rapidly lost in the presence of T(4) by a ubiquitin-proteasomal mechanism. In the present study, we demonstrate that D2 and TSH are coexpressed in rat pituitary thyrotrophs and that hypothyroidism increases D2 expression in these cells. Studies using two murine-derived thyrotroph cells, TtT-97 and TalphaT1, demonstrate high expression of D2 in thyrotrophs and confirm its sensitivity to negative regulation by T(4)-induced proteasomal degradation of this enzyme. Despite this, expression of the Dio2 gene in TalphaT1 cells is higher than their T(4)-induced D2 ubiquitinating capacity. As a result, D2 activity and net T(3) production in these cells are sustained, even at free T(4) concentrations that are severalfold above the physiological range. In this system, free T(4) concentrations and net D2-mediated T(3) production correlated negatively with TSHbeta gene expression. These results resolve the apparent paradox between the homeostatic regulation of D2 and its role in mediating the critical mechanism by which T(4) triggers the TSH-negative feedback.
Collapse
Affiliation(s)
- Marcelo A Christoffolete
- Thyroid Section, Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Sharma V, Hays WR, Wood WM, Pugazhenthi U, St Germain DL, Bianco AC, Krezel W, Chambon P, Haugen BR. Effects of rexinoids on thyrotrope function and the hypothalamic-pituitary-thyroid axis. Endocrinology 2006; 147:1438-51. [PMID: 16306084 DOI: 10.1210/en.2005-0706] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Retinoid X receptor (RXR)-selective retinoids (rexinoids) can cause central hypothyroidism in humans, and this effect has been confirmed in rodent models. In this report, we characterized the effect of rexinoids on the hypothalamic-pituitary-thyroid axis in mice and TSH regulation in a thyrotrope-derived cell line. The synthetic rexinoid (LG 268) suppressed TSH and T4 levels in mice. Hypothalamic TRH mRNA was unaffected, but steady-state pituitary TSHbeta mRNA levels were significantly lowered, suggesting a direct effect of rexinoids on thyrotropes. LG 268 suppressed TSH protein secretion and TSHbeta mRNA in TalphaT1 thyrotropes as early as 8 h after treatment, whereas the retinoic acid receptor-selective retinoid (TTNPB) had no effect. Type 2 iodothyronine deiodinase (D2) mRNA and activity were suppressed by LG 268 in TalphaT1 cells, whereas only D2 mRNA was suppressed in mouse pituitaries. LG 268 suppressed TSHbeta promoter activity by 42% and the -200 to -149 region accounted for a majority of the LG 268-mediated suppression of promoter activity. The RXRgamma isotype is expressed in thyrotropes. In vitro transfection and in vivo transgenic studies indicate that any RXR isotype can mediate TSH suppression by rexinoids, but the RXRgamma isotype is most efficient at mediating this response. RXRgamma-deficient mice lacked pituitary D2 mRNA suppression by LG 268, but D2 activity remained intact. In summary, RXR-selective retinoids (rexinoids) have multiple effects on the hypothalamic-pituitary-thyroid axis. Rexinoids directly suppress TSH secretion, TSHbeta mRNA levels and promoter activity, and D2 mRNA levels but have no direct effect on hypothalamic TRH levels. Rexinoids also stimulate type 1 iodothyronine deiodinase activity in the liver and pituitary.
Collapse
Affiliation(s)
- Vibha Sharma
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado at Denver and Health Sciences Center, MS 8106, P.O. Box 6511, Aurora, Colorado 80045, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Sarapura VD, Wood WM, Woodmansee WW, Haakinson DJ, Dowding JM, Gordon DF, Ridgway EC. Pituitary tumors arising from glycoprotein hormone alpha-subunit-deficient mice contain transcription factors and receptors present in thyrotropes. Pituitary 2006; 9:11-8. [PMID: 16703404 DOI: 10.1007/s11102-006-7865-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Glycoprotein-hormone alpha-subunit deficient (alphaSUnull) mice are hypothyroid and hypogonadal due to the absence of functional TSH, LH and FSH, despite normal production of the corresponding beta subunits. Pituitary tumors spontaneously developing in alphaSUnull mice were propagated in hypothyroid mice. The purpose of the current studies was to compare the gene expression profile of these alphaSUnull tumors with previously characterized TtT-97 thyrotropic tumors. A group of animals bearing each tumor type was treated with thyroid hormone (T4) prior to tumor removal. Both tumor types equally expressed TSHbeta mRNA, which significantly decreased when exposed to T4, whereas alpha-subunit mRNA was absent in alphaSUnull tumors. Northern blot analysis was performed using cDNA probes for the following transcription factors: Pit1, GATA2, pLIM, Msx1, Ptx1 and Ptx2. Both tumors were found to contain identical transcripts with similar responses to T4, with the exception of Pit1. In contrast to the signal pattern seen in TtT-97, only two bands were seen in alphaSUnull tumors, which were similar in size to those in alphaTSH cells, a thyrotropic cell line that lacks TSHbeta-subunit expression and Pit1 protein. However, western blot analysis revealed a protein band in the alphaSUnull tumors consistent with Pit1, while this signal was absent in alphaTSH cells. Northern blot analysis was also performed with specific cDNA probes for the following receptors: TRbeta1, TRbeta2, TRalpha1, non-T3 binding alpha2, RXRgamma and Sst5. Similarly-sized transcripts were found in both types of tumor, although the signal for Sst5 was seen in T4-treated alphaSUnull tumors only with a more sensitive RT-PCR analysis. The overall similarity between the two tumor types renders the alphaSUnull tumor as a suitable thyrotropic tumor model.
Collapse
Affiliation(s)
- Virginia D Sarapura
- Department of Medicine, Division of Endocrinology, University of Colorado Health Sciences Center, Denver, CO 80045, USA.
| | | | | | | | | | | | | |
Collapse
|
34
|
Woodmansee WW, Kerr JM, Tucker EA, Mitchell JR, Haakinson DJ, Gordon DF, Ridgway EC, Wood WM. The proliferative status of thyrotropes is dependent on modulation of specific cell cycle regulators by thyroid hormone. Endocrinology 2006; 147:272-82. [PMID: 16223861 DOI: 10.1210/en.2005-1013] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In this report we have examined changes in cell growth parameters, cell cycle effectors, and signaling pathways that accompany thyrotrope growth arrest by thyroid hormone (TH) and growth resumption after its withdrawal. Flow cytometry and immunohistochemistry of proliferation markers demonstrated that TH treatment of thyrotrope tumors resulted in a reduction in the fraction of cells in S-phase that is restored upon TH withdrawal. This is accompanied by dephosphorylation and rephosphorylation of retinoblastoma (Rb) protein. The expression levels of cyclin-dependent kinase 2 and cyclin A, as well as cyclin-dependent kinase 1 and cyclin B, were decreased by TH, and after withdrawal not only did these regulators of Rb phosphorylation and mitosis increase in their expression but so too did the D1 and D3 cyclins. We also noted a rapid induction and subsequent disappearance of the type 5 receptor for the growth inhibitor somatostatin with TH treatment and withdrawal, respectively. Because somatostatin can arrest growth by activating MAPK pathways, we examined these pathways in TtT-97 tumors and found that the ERK pathway and several of its upstream and downstream effectors, including cAMP response element binding protein, were activated with TH treatment and deactivated after its withdrawal. This led to the hypothesis that TH, acting through increased type 5 somatostatin receptor, could activate the ERK pathway leading to cAMP response element binding protein-dependent decreased expression of critical cell cycle proteins, specifically cyclin A, resulting in hypophosphorylation of Rb and its subsequent arrest of S-phase progression. These processes are reversed when TH is withdrawn, resulting in an increase in the fraction of S-phase cells.
Collapse
Affiliation(s)
- Whitney W Woodmansee
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado at Denver and Health Sciences Center, Aurora, Colorado 80045, USA
| | | | | | | | | | | | | | | |
Collapse
|
35
|
Abstract
T3 suppression of TSH subunit gene transcription is an important step in maintaining thyroid hormone homeostasis, and recent investigations have increased our understanding of this process. Thyrotrope-specific proteins play a critical role in TSH subunit gene expression, and influence T3-mediated regulatory mechanisms. The structure and placement of the TSH gene TREs define suppressive regulation by T3, and this process is favored by the TR isoforms expressed in the pituitary. Elimination of TR beta function compromises the pituitary response to T3. TR beta 2, the isoform specifically expressed in pituitary and neural tissue, contains a transferable domain that both increases T3-independent gene transcription and enhances T3-suppressed transcription. The functional interaction of TR beta 2 with other regulatory proteins is distinct from that of other TR isoforms, and likely plays a critical role in pituitary physiology and in pituitary resistance to thyroid hormone. The development of novel thyrotrope cell lines will allow investigators to define new proteins and molecular mechanisms that distinguish negative from positive T3 transcriptional regulation.
Collapse
Affiliation(s)
- M A Shupnik
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Virginia Medical School, Charlottesville, VA 22903, USA.
| |
Collapse
|